Thermal ink-jet printers offer a low cost, high quality, and comparatively noise free option to other types of printers commonly used with computers. Such printers employ a resistor element in a chamber provided with an egress for ink to enter from a plenum. The plenum is connected to a reservoir for storing the ink. A plurality of such resistor elements are arranged in a particular pattern, called a primitive, in a printhead. Each resistor element is associated with a nozzle in a nozzle plate, through which ink is expelled toward a print medium. The entire assembly of printhead and reservoir comprise an ink-jet pen.
In operation, each resistor element is connected via a conductive trace to a microprocessor, where current carrying signals cause one or more selected elements to heat up. The heating creates a bubble of ink in the chamber, which is expelled through the nozzle toward the print medium. In this way, firing of a plurality of such resistor elements in a particular order in a given primitive forms alphanumeric characters, performs area fill, and provides other print capabilities on the medium.
The present construction of printheads in thermal ink-jet print cartridges employs nickel as the orifice plate material. Since inks corrode nickel, a gold layer (electroplated gold) is formed on the surface of the nickel as a corrosion barrier. The orifice plate is bonded to the barrier layer by a thermal cure cycle.
Problems also exist with the use of adhesives for securing the orifice plate. Adhesives do not provide a uniform coating and often cover the holes in the orifice plate.
A need remains for a material useful in the construction of thermal ink-jet printheads as an orifice coating which improves the securing of the orifice plate to the barrier material, improves corrosion resistance, and eliminates costly gold plating.